L. MECHANICS AND ENGINEERING. 461 



culty of rolling the flanged iron sides. This, however, has 

 been successfully overcome, and the new invention promises 

 to come into rapid use. 3 A, October 18, 1873, 477. 



NEW METHOD OF PRESERVING WOOD. 



A new method of preserving wood from decay has been 

 recommended by Hatzfeld. It seems that, in 1830, speci- 

 mens of oak were dug up in Rouen which had been buried 

 since the year 1150. This wood was quite sound, but had 

 acquired a black color like ebony, and an astonishing hard- 

 ness. Hatzfeld ascribed its preservation to the joint action 

 of the tannin in the wood and the oxides of iron in the soil. 

 Accordingly he now proposes to preserve wood artificially 

 by means of tannin and the pyrol ignite of iron, a combina- 

 tion which would in some measure bring about the same 

 changes noticed in the specimens from Rouen. Hatzfeld im- 

 pregnates the wood to be preserved, first with tannin, and 

 subsequently with the pyrolignite solution. The latter sub- 

 stance has long been used by itself as a preservative of the 

 best character, and it is doubtful whether the addition of the 

 tannin, as proposed by Hatzfeld, will prove of sufficient ad- 

 vantage to warrant the extra expense. 8 C, December 25, 

 1873,430. 



THE AEROPHORE. 



The aerophore, a new life-saving apparatus, is at present 

 attracting much attention. It is specially designed to enable 

 the workman or miner to enter a mine full of fire-damp, and 

 to labor there with complete immunity from danger. Its 

 continuous action seems to be its chief and very excellent 

 merit. As designed for coal-mines, the apparatus consists of 

 an air-pump, a regulator, a strainer, an air-tube, w r ound on a 

 self-regulating coil, and a lamp. 



The regulator, weighing about eight pounds, is strapped 

 upon the back, and supplies the wearer and his lamp with 

 fresh air. In construction, it is a metal box, so divided and 

 fitted with valves that, on breathing into it, the breath is ex- 

 pelled and fresh air supplied to subsequent inhalation, at nor- 

 mal pressure and in proper quantity. One chamber is sup- 

 plied with compressed air, obtained and kept up from the 

 pump, and from reservoirs, where it is found impracticable to 



